1. Field of the Invention
The invention relates to a circuit arrangement for displacing characters representing an image content of the screen of a data viewing device in which the characters are represented in a plurality of rows and a plurality of columns, and in which an electron beam is moved by a first deflection signal in the vertical direction and by a second deflection signal in the horizontal direction over the screen.
2. Description of the Prior Art
It is already known in the art to displace characters on the screen of a data viewing device when the number of characters to be represented is greater than the number of characters which can be represented on the screen. In these known data viewing devices, the characters on the screen are displaced by rows in the upward or the downward direction. New characters are represented in the rows which are thus free. This type of displacement of characters is known as the "rolling page" function. An article by J. Hochmuth and Hermann Lang, Datensichtstation Transdata 8152 for Graphik und Alphanumerik, Siemens-Zeitschrift 48 (1974) Ed. 1, for example, describes a row-by-row displacement of the characters in the upward direction known as "roll up."
The known data viewing devices in which the characters are displaced by rows and by stages have the disadvantage that as a result of the sudden change in the rows, it is often very difficult to read out the characters on the screen.